The present invention generally relates to digital video signal transmitting apparatuses, and more particularly to a transmitting apparatus which transmits a digital video signal made up of picture element data corresponding to one field, by dividing the digital video signal into a plurality of picture element groups each corresponding to less than one field, to store the data of the digital video signal into a memory, and obtains a reproduced video signal by reading the same stored data from the memory a plurality of times.
When the signal-to-noise level at the time of the reproduction is over a predetermined value, a digital signal can be restored back to the original digital signal. Hence, in order to carry out recording and reproduction of a high quality, a digital video signal is recorded on and reproduced from a recording medium such as a magnetic tape and a disc. The digital video signal is obtained by subjecting an analog video signal to a digital pulse modulation such as a pulse code modulation, for example. In this case, when transmitting a digital video signal related to a still picture or related to a so-called partially moving picture in which only a part of the picture contains a movement, it is desirable to transmit as much video information as possible under the limitation of the recording capacity of the recording medium. Thus, a digital video signal corresponding to one field which is less than one frame which is originally to be reproduced was transmitted, or a so-called differential transmitting method was employed in the case of the partially moving picture, for example. According to the differential transmitting method, the frame correlation of the video information was noted, and a differential data between the picture element data of one frame and the picture element data of a subsequent frame was transmitted when the subsequent frame included picture element data different from the picture element data in the one frame.
When transmitting the digital video signal corresponding to one field, only the data related to the picture elements in one of first and second fields (odd and even fields) were transmitted among the picture elements which are arranged in a matrix form to make up one picture. For this reason, the vertical resolution of the reproduced picture obtained in this case, inevitably became poorer than the vertical resolution of the reproduced picture obtained when all of the picture element data corresponding to one frame was transmitted. Further, the folding noise increased, and when the picture contained an oblique line, for example, the oblique line was reproduced as a stepped line. Moreover, when the picture contained horizontal lines which differed in their thicknesses and positions, these differences were over-emphasized in the reproduced picture.
In addition, in a case where the differential transmitting method was employed and a large portion of the picture changed to a different picture, the different picture could not be displayed in the large portion of the picture until all of the digital video signals (picture element data) related to the different picture were stored into the memory within the reproducing apparatus. As a result, it took a long time to change the display in the large portion of the picture to the different picture.